As a non-aqueous electrolyte solution for secondary batteries such as lithium secondary batteries and lithium-ion secondary batteries, a non-aqueous electrolyte solution (1) containing an inorganic lithium salt such as LiPF6 or LiBF4 is used because of its high conductivity and excellent withstand voltage properties.
Further, as an electrolyte salt, a non-aqueous electrolyte solution (2) wherein a bis-(sulfonyl)imide lithium salt such as Li[N(SO2—CFH—CF3)2] or Li[N(SO2—CH2—CF3)2] is used as the main component (at least 60 mol % based on 100 mol % of the total electrolyte salts) is also known (Patent Document 1).